The New Sith Empire 3,970 BBY: After the Mandalorian Wars, the Revanchist returned to Dantooine with his friend Alek where they stmbled upon an ancient temple where they found a Star Map. They were told where to find this map by the remnents of the first Sith Empire in the outer regions. They were told to serve as a Vanguard for them. This Star Map led to many more where they found the Star Forge, a Rakatan war devise they built an Empire out of. They built an Entire Armada and using the troops and Dark Jedi given to them by the Sith Emperor, they corrupted many republic soldiers and eventually the Jedi. The first to join were the remnent forces from Exar Kun and Revan's old Master, Darth Traya and her two apprentices Nihilus and Lucien Draay AKA Darth Sion. The three however believed that Revan was ruling his "Empire" in a different manner than the Emperor wished, so she broke away and formed the Sith Triumverite and captured Malachor from Revan. Revan was however defeated by his master and the Jedi and was captured. The Empire finally fell however when Revan attacked the Star Forge, Malak's last place of refuge and destroyed it along with him. Revan went into the outer regions to try and stop the True Sith. The two rulers, of course, are Darth Revan and Darth Malak.

Here is a more correct interpretation: A powerful Jedi (known as Revan) started the Revanchist movement to help the Republic defeat the Mandalorians. During the ongoing conflict (The Mandalorian Wars), Revan learned about the significance of a planet Malachor V and the taboo it presented to the Mandalorians. Revan visited this planet and got exposure to vast amounts of the Sith Lore. He also learned about the existence of the True Sith there. After the conclusion of the Mandalorian Wars, Revan and Malak in pursuit of remnants of the Mandalorians in the unknown regions met the Sith Emperor (leader of the True Sith) in Dromund Kass. The Emperor persuaded them to prepare for invasion of the Republic by Sith. The fall of Revan and Malak to the dark side was now complete. The two returned as Master and Apprentice. However, their ambitions grew as they got nearer to acquisition of an ancient entity of great power - The Star Forge. Both Revan and Malak now envisioned their own Sith Empire. Revan specially planned to use the combined power of the Republic (under his command with its infrastructure intact) and the Star Forge to counter the threat posed by the Sith Emperor. In short: The Revan was preparing to challenge the Sith Emperor. To achieve his aims, Revan established a Sith Empire of his own and initiated Jedi Civil War to conquer the Republic. However, Darth Malak shattered his hopes by betraying him and got the chance to carry out his own ambitions. Unbeknownst to him, Revan survived and ended Malak's quest to rule the Galaxy by killing him. The Sith Empire crumbled and Star Forge was destroyed. Revan was now hailed as a legend and a great Jedi hero. However, from the ashes, Sith Triumvirate was born.

Sidenote: Keep in mind that Kriea became a Sith Lord after the conclusion of the Jedi Civil War and she formed Sith Triumvirate with assistance from Darth Sion and Darth Nihilus, who at one time were her apprentices. However, she was betrayed and was instrumental in downfall of the other two Sith Lords. Ironically! Her new apprentice - The Jedi Exile - killed her too.